If you've already bought the baskets then you need a steamer which you don't have because they are huge and only restaurants use them.  What you can do is buy a huge wok and a steel frame to put inside it.  Then you can put some shallow water in the wok, and rest the steamer basket on the frame.  Cover the wok and it will steam your dim sum.  The steel frames are pretty easy to find but your basket might be too large because they're designed to be used with the industrial sized steamers.

BUT>>>

The easiest way is to buy a rice cooker. They usually always have a plastic frame that sits at the top of the cooker to steam things like man tou 馒头.  You can put the dim sum directly on that when you're cooking rice, or simply put some water in without rice to steam them.

You can get steamers real cheap on Taobao, my girlfriend didn't pay more than 80RMB for ours. It broke when I tried to use it to cook pancakes (funny story) so we sent it back and they fixed it..  From then on, we only use it for boiling water.

We use our steamer a lot, almost everyday.. Bread with custard inside, bread with egg yolk inside, bread with sweet black paste, bread with sweet red paste, bread with pork inside, bread with BBQ meat inside, the black cabbage leaves with the sticky rice inside and then the pork inside the sticky rice. It can cook a lot of things.

We don't use the bamboo baskets because they tend to be a bit more expensive than a little pan with holes in it.. You can buy the bamboo baskets on taobao if you like, but they're not really needed to cook nice food and they're a PITA to clean.