You can do a block selection of the beginning of the lines you want to indent. Then hit tab, and a tab will be inserted on each line.
Even better, you can use Dynamic Surround. When you type if followed by a space, Syntax Expansion puts in the rest of your if statement. It also draws some blue lines. If you hit down arrow, the blue line will move down one line and pull that line of code into the newly inserted block. When it hits a block, like the one you're trying to include, it pulls the whole block in and indents it.