1999 Pontiac Grand Am

Well quite frankly I don't know whats happening to my car. First of all it has a security issue and sometimes wont start. I then have to wait 15 min. For it to reset its security system and try it again not always being successful. It doesn't start right up, ever. I always have to hold it while it cranks for 3-6 seconds. Sometimes it starts and catches, other times itll start, idle for a moment then die. But the big problem is the other day driving through town, while driving it died over 10 times. The RPM gauge twitches then it dies like im out of gas. It even shuts down going down the highway. Im an 18 year old college girl, im low on m oney and I dont know a lot about cars. Whats wrong with my car? Is it worth fixing?