Planting/Gardening Help?

Hi everyone! I'm going to plant heirloom canteloupe, heirloom tomatoes, and sugar snap peas. And I'm not sure how far apart they should be spaced when I put the seeds into the ground. I know it says on the package but I have a hard time reading that for some reason... But anyways my question is How far apart do each of the 3 types of seeds need to be planted? And another thing, my garden is basicly just gonna be a wooden box filled with soil and also need to know how tall it should be for the roots to grow sufficiently? Sorry if this sounds all stupid and jumbled up. I'm not really familiar with this stuff.