Sometimes they become one word:
flatmate (noun)
lovesick (adjective)
Sometimes they become two words:
tourist guide (noun)
travel agent (noun)
Sometimes they become hyphenated:
low-paid (adjective)
film-goer (noun)
Note: There are no hard and fast rules about which category each compound word goes into but a good dictionary will tell you. You can also help yourself by making a note of new compound words you come across and the category they go into.
Generally the stress is on the first word:
phone box (noun)
smoke-free (adjective)
spoon-feed (verb)
Vocabulary:
a flatmate (n):
a person who shares a rented house or flat with other people
lovesick (adj):
a feeling of such strong emotion for someone that it makes you feel almost ill (but not actually physically ill)
a tourist guide (n):
someone who shows visitors around places of interest
low-paid (adj):
earning a small amount of money for working
to spoon-feed (v):
to feed someone (usually a baby) with a spoon or to give someone so much information or help that a task or job is very easy for them