League of Legends (LoL) Question: What software should i use to put my video, screenshots, gifs to my guide?

You don't need any software to put videos/screenshots in your guide, just use the BBCode.

If you want something to record the videos, then I recommend OBS, it is free and has a good quality/performance impact.

If you want to put a video in a guide, upload it to YouTube (for instance) and then copy the link and use the "embed" code. For gifs and pictures, use the "insert picture" code.