If it's running the Lollipop flavour of Android, you start by going into Settings then Storage and nominate the SD Card as Internal Storage as opposed to Portable.
That way, it becomes an annexe to the built-in storage and some Applications can be moved. Some cannot be because they need to live in the system folders.
To find out which ones you can move, right click on an App and see if moving to SdCard is an option on offer.
If none of them can be moved, it may be your retailer or service provider have prevented it to encourage you to buy a new device with more built-in storage.