First grow - Need help

[Tomatogrower]

Hey guys. This is my first time growing and I'm running into a bit of a problem with a few of my plants. I was hoping someone could help me figure out what's wrong with them. First of all, one of them has leaves that have burned up really bad. It's only the old leaves, not the new ones. It doesn't look like nutrient burn so I'm a little confused. The next plant has some weird marks on the top leaves and I'm thinking it's just light burn but I wanted to run it by you guys. Your advice is greatly appreciated. Thanks.
-Tomatogrower

 

[Tomatogrower]

Ok guys I'm starting to see signs of that burn in other plants now. I put some gypsum (calcium and sulfur mix, mostly calcium) near the base and watered it in as well as sprayed it on the leaves. I noticed when I spray water on the leaves I can see spots on the leaves, like there is salt. I know gypsum should push the salts down and clean the soil. I'm hoping this works. Any advice would be great. Here's some more pics. This is with gypsum on the leaves.

 

[Tomatogrower]