I am playing ingress. In my current area two of the three portals are owned by the enemy. I have been able to "hack" these portals but it will not allow me to use my XMP bursters. I am only a first day player at level one, but I have lvl 1 and 2 xmp bursters. why cant I use them on these portals?
You can only use XMP bursters of your level or lower, so for you that's Level 1 bursters.
What do you mean it won't "allow" you to use the XMP?
There are two ways to fire XMP. From the inventory menu, select "Fire" while viewing one of your XMP bursters. The second, and to me the easiest way, is to long-press on the scanner screen and then tap the "Fire XMP" menu option that appears. This will automatically fire the highest-level XMP burster you have access to.
Note as well that you have to have some XM to fire an XMP. If you've been hacking enemy portals and they've been hitting you in response, you may have run out of XM. Also Level 1 XMP are very weak; you should be standing on top of a resonator in order to destroy it, and even then it will probably take more than one XMP.