Here are some basic tips for you
At your level for single targets (like bosses), your ice phases will be Blizz 3, enochian (if not up), Blizz 4 to get umbral hearts, and your highest single target thunder. Your fire phases will be Fire 3, Fire 4 x3, Fire 1 to keep your astral fire buff (fire 4 does not refresh it), and another Fire 4 x3. You'll also want to fit any instant procs in there (thunder, instant fire 3) as long as you aren't in danger of your fire/ice buff dropping. There's more stuff to add to this in your 70s, but that's where more detailed guides can help. Essentially, your goals are to keep Enochian up and cast as much Fire 4 as possible.
Whenever you have 3 or more targets, you want to do an AoE rotation instead. Ice phases with be Freeze followed by an AoE thunder, then you can go into fire phase with fire 3
followed by fire 2 spam then fire 2 x 2, and a flare to finish - then transpose into ice to continue. At 68 you get a special trait that simplifies this even more; your fire phase is just Fire 3, Flare x2, the end. Again, keep using those thunder procs.
And finally, at 72 youll get another trait that lets you cast an ice spell for 0 mana when you have full fire stacks. Use this to more smoothly switch back to ice(freeze spell) after flare drains you.
These basics should get you in reasonably average shape at your level.

It sounds like a lot, but it's only like~ 9 spells for your core gameplay til 70+ starts adding things like Foul and Despair.