Control line flying can be interesting. It won't hurt to try it.

A .15 engine, you typically use .012 stranded steel lines, 50 to 55 ft long.

When learning to fly them... you want relatively little control. You want to learn to "dance" in a circle following the airplane as it goes in circles. As you get used to that, you slowly add more control throw to the model. And you start with a SMALL fuel tank at first... 5 laps (about 30 sec) will be enough your first flight. (don't want to crash due to being dizzy.)

Without knowing which model you have... and its condition, hard to say if you should try to fly that one as is... repair it... or try a different aircraft.