I want to use that kind of put the jar file into the mods folder.I put the XRay-47.jar file in the mods folder but the game does not load the jar file. The version I am using is 1.8.8 in the server.
If you're only want to drag & drop it into the mod folder - I assume you've already installed Forge ??
If you haven't installed Forge then you need to download the version from the website for the version you want (in your case 1.8.8)
Vanilla Minecraft cannot see anything in the mods folder without a little help
For almost all versions - You would usually need Forge, it's the most popular and longest running mod loader around,although they can be a little slow sometimes updating to the latest version. (IIRC due to massive code changes in 1.13 & 1.14 it's taken them longer to update this time around)
Before 'Forge' got updated, you would've needed 'Rift' for 1.13, & 'Fabric' for 1.14+ but these required mods specially written to work; (most) forge mods wouldn't work with these mod loaders
dont know if this is stated allready or not, but uhm, i cant install the mod atleast the one on page 179, but uh i cant install it into my 1.14.2 forge thing, and it also doesent load into forge when i launch it because i put the jar in my mods folder.