How should I fix these seedlings into a starter pot?

I watered some seedlings (er Crunch Lettuce) and now they have sprout. They're about 1/8th of an inch so I need to put them into little pots. how many inches away from eachother can I plant them. I'm using small plastic containers for now until they can be moved to a larger pot. Do I need to cut holes in the bottom for drainage. These containers don't have holes in them already.?