Just a little bit more input after @IPATEAM has posted the correct link to give you more information about bonding. It looks like you would not really want bonded interfaces but some kind of loadbalancing.
First: There is a little misunderstanding out there about having multiple uplinks on one router. Its not possible to just "bond" those two lines together and get one big uplink in return. But you are able to either load-balance your connections over those two ISPs or use one as primary and the second as fallback if there are any errors on line 1. The following wiki article will help you to understand that a little bit better:
In your situation i would try to learn about the dis-/advantages of Failover (Article 2.1) and ECMP (Article 2.3) and decide for one of those. If you have any problems with the configuration dont hesitate to ask. But read the wiki article first