1. Go to snapchat official site https://www.snapchat.com than go to download menu and choose snatchat for blackberry.
2. Than download it into your pc, joined your blackberry mobile via USB to your pc and send it to your blackberry.
3. G to application folder in your blackberry where file send after downloading and start installing.
4. Thats it, you have completely download snapchat app in your blackberry mobile.
Note: This snapchat version works for all blackberry mobiles including blackberry z10, blackberry q10, blackberry curve, blackberry bold, blackberry playbook