Normally you update your working copy using TortoiseSVN → Update. But if you only want to pick up some new files that a colleague has added without merging in any changes to other files at the same time, you need a different approach.

Use TortoiseSVN → Check for Modifications. and click on Check repository to see what has changed in the repository. Select the files you want to update locally, then use the context menu to update just those files.