Hi, first of all, welcome! to start you must learn the bnb combos, they make you understand the basic function of all the movements of the characters so that you can get an idea if the ability they have to make combos and how to connect them, I recommend that you take a look
HERE, where you can check squigly's bnb combos and those of other characters too, they are quite usefull for those learning squigly because of her stance mechanics, also
HERE is a very complete guide for squigly, it includes terminology and imput menanings for you to understand them in case you don't know them already, if you still want to learn more
HERE is another squigly guide, it might be outdated because of encore changes but it is still quite usefull and well explained, you should take a look at it, also you can join the
Skullgirls discord server where you can learn more combos, assist synergy with different characters and ask for online battles if you want to practice, hopefully that was usefull for you.