Welcome to the forum.
You will be able to put together a 500 point army from the battalion box.
At this point cap, you have the choice between using a Saurus Scar Veteran or a Skink Priest as your general, both has their cons and pros.
If you do not want to use skink priests atm. then this could be a possible list:
Saurus Scar-Veteran (General) (Just use one of your saurus warriors as a scar vet, perhaps paint him a little different)
12 Saurus Warriors
10 Skink Skirmishers
5 Cold One Riders
Here you would fill your quota up to the allowed Hero points limit tooling up the Scar Veteran (i.e. give it the desired magic equipment).
You also have seven more saurus warriors, and two more skinks in the box, so you could take less cold one riders and more of those instead.
In regards to the skink priest, I strongly recommend that you also try to play using that, as even if there is another one using lizardmen that does not mean that you should not use X unit.
Also if you feel that putting together a list is difficult, there is a good software called "Army Builder", I think it cost like 20 dollars for a license (but you can test it for free). As you make an army it will tell you if your choices are valid or not and show you what is wrong.
And as you put together an army, feel free to post on our army forum for feedback.
Good luck with your army!