Taste of pre-frozen lasagna

350F is the magic temp. Just about every casserole cooks at 350, and you cook it until it starts being bubbly which will probably between 30 minutes and an hour (in this case, you should check to make sure it's hot in the center as well, since you're starting from frozen). I'd cover it early, and then uncover it near the end so the top won't get dry.

The general process of making lasagna is:

• Cook the other ingredients - brown the meat in a pan (maybe with seasonings); if you're using fresh tomatoes, cook them; if you're using canned tomatoes, drain the extra liquid out. The important thing is that everything is cooked, and there's not too much liquid left, since that'd make the lasagna messy at the end. This does mean it's faster with canned tomatoes, since you only have to drain them, not cook them.
• Cook the noodles as you would any pasta. Be sure to stir, since big flat noodles stick together more easily than most. (There are also no-boil lasagna noodles, but you've already bought yours, and I doubt that's what you have.)
• Layer the ingredients in the pan, starting with sauce on the bottom (otherwise the noodles will stick to the pan), then noodles, then alternate layers of the other ingredients and noodles and sauce until you run out or your lasagna dish is full.
• Bake it until it's heated through (the ingredients are all already cooked).
• Let it cool for a bit before serving; this helps keep it from falling apart when you cut into it.

When you go looking for recipes, though there are tons and tons of them, they'll pretty much all look generally like this. They'll just have variations in ingredient proportions, seasonings, order of layers, and so on. You shouldn't have trouble finding one that matches up with the ingredients you have, if you want a recipe to follow carefully. As long as it generally matches the steps I listed, it should be fine.