you need to learn by doing, while observing and learning from videos you see, watch tutorials on youtube, and learn your way into Vegas as you experiment and look for the things you need and want to accomplish. RTM. Google picture in picture FX on YT, compositing, text generators etc etc, you'll have to work your way into and through it step by step. It's not that hard, it's just work, dedication and curiosity, and there's always this forum to help you with specific difficulties.
you need to do some more thinking , experimenting, trial& error and searching by and for yourself before asking for help. It's really not that hard. Vegas also has a manual, and YT is full of tutorials for any workflow and any kind of issue. This forum will give any necessary help with problems you then meet along the way in your work.