add object to an array

Hi

im trying to create an array that will hold 4 exchange databases info in it.

for so I start with:

@dbs=get-mailboxdatabase db1

works fine

then I try to add more databases like this but I get errors:

@dbs +=get-mailboxdatabase db2

what am I missing here?

should I create an empty array first and then add them into it?

also is there away to run all 4 commands(for db1-4) in one liner and store it as variable/array?

Thanks