I have made a LiveSplit file for the game I want to run, but whenever I try opening it, it asks,"How do you want to open this type of file?" What should I do? Also, LiveSplit itself will not open.

If Livesplit won't open your best bet is to re-install and see if that fixes the issue and lets you run it. But once livesplit opens, in order to open a livesplit file (.lss) then you just right click on Livesplit and say "open splits" and then pick the .lss file you want to open

Open Livesplits , there is a button Open splits