PC How can I get the dang spell casting to work spells scrolls

[Anarchist51]

I hope this is the last question for today: OK I got magic and the power but when I try to cast a spell or use a scroll I cannot for the life of me get the dang thing to work. Eventually it kind of goes if I keep hitting the M1 and M2 but mostly just fizzles out or doesn't go off.
If I try to use magic in combat I get killed almost immediately. I just cannot figure out what I am doing wrong. I end up using a sword to fight.