buy a rose plant. remove from wrapping and soak neck-deep in a bucket of water overnight. plant out according to instructions on packet, preferably in direct sunlight. water well. you'll need to read up on pruning also, and when to prune.
try and find a good nursey (garden, not kids) as they are more likely to be 'grown hard' and should takeeasier. look at info tickets on plant to see if they prefer sun/shade etc.. then think about where in your garden you want rose. plant with plant food and don't put other plants too near it (they are a bit princessy) o hang on, am starting to repeat sound advice already given.
Once you start growing roses, your question will probably be how to stop them. Most roses, once they take hold, are virtually indestructible. Oh, and very thorny too. I would buy some plastic ones - nice colours and longer lasting. And you can wash the dust off them.