I've been trying to look it up on the internet for awhile now, but can't find anything. I have a Windows 10 PC with the original Java edition that I ported over from my previous PC or something like that. It's been awhile since I've even played Minecraft. I can't seem to use the installer for the more recent two versions. 1.12 had a tab for Win-installer, but not 1.13 and 1.14. The .jar file won't open without an App apparently. Is there a remedy to this situation or do I need to wait until there's a Win-installer for the newer versions as well? All I'm really trying to get right now is Optifine as most of my favorite mods seem to be dead. (namely Twilight Forest, Backpacks, Colourful Portals, and Millenaire)
Also, I can't remember how to log in with my original Minecraft Forum name, but that's another topic. I had one from before for just the site, not Twitch.
When installing Forge or any modloader for that matter in any version of Minecraft it is best to download and install Java 32bit or 64bit first. Then install Forge for the modded version your after. I myself never use the Win Installer since I'm used to the Java one then I make sure the profile for Forge is installed and visible (if Forge 1.12.2 and prior the Forge version appears below Release 1.0, for 1.13+ it appears within the Release 1.13 and 1.14 versions). If Forge is loaded correctly and the Forge install text is in the bottom left of the game then it is working. Then just add mods and their cores or libraries if those mods need them and your good to go. If it crashes just disable or remove the mods to see which work and which don't.
Other than that Optifine should work in the mods folder, so no installing it as that is for Optifine to run alongside Vanilla, if it doesn't work by just being in the mods folder (if 1.13 and up deeper folders than .minecraft/mods won't work so they must be in the mods folder, if 1.12.2 and prior it's best to put them into a 1.12.2 folder so Forge can still read the mods but not conflict with your 1.13 or 1.14 ones, (unless maybe JEI doesn't want to work when attempting to load 1.12.2 but notices the 1.14 one in the mods folder instead of ignoring it so I have to separate them because that's always fun XD).
If you could show any images that would be great but for now that's all I can think of saying towards Forge and Optifine being setup correctly. If there is any other issues let me know.
Well, I found out about the Twitch thing afterward. However, I have no idea how to manually add Optifine to it. Opfitine says you need Forge. All I really want is Optifine. I apparently get an error when trying to open the Launchers even now that I got Java opening the files now, rather than the stupid wordpad thing that somehow happened. (It asked me to choose an app to open the Jar files with and I stupidly clicked on Wordpad by accident.) I've uninstalled and re-installed Java and it still says something about an unable to install Java. Check that the commands are valid and try again on both Forge installer and Optifine's.
I tried putting it directly into the Mods folder, but Optifine wouldn't work. Something about being unsupported.
I'm unable to help with the command parts since I don't know how to do that but when it comes to Forge 1.14 and Optifine, Optifine isn't Forge 1.14 supported yet, only Fabric, another modloader that came about before Forge 1.13 and 14 supports Optifine with a mod called OptiFabric.
Optifine does work for 1.12.2. below versions of Forge but not 1.13.2 or 1.14+ as far as I know. This may change in the future but Forge might not have the requirements for Optifine to add support since the Forge team not only restructured Forge for the 1.13 ID changes but also took months to remove legacy code and rework it's self. So the support Optifine needs isn't available yet with Forge still I guess, I don't know as I never use Optifine myself but have when questions are asked about it I install it and see what happens.
If all you want is Optifine and no mods then just install Optifine by double clicking and Installing it, then it will create a profile for you to play Vanilla and Optifine, all the other things that are necessary towards Modloaders is the extraction of Optifine (only if nothing else works) or putting it in the mods folder alongside mods and a version of the game that supports it like I said above.