I'll help ya out.
To use wire cutters (I assume you mean in
Chasing Shadows), simply walk into the section in the fence which you must cut. Note this is a predetermined spot which is marked on map.
To use Dynamite, first make sure you have some in inventory by pressing
I by default, then hit the gear icon in the controls area. You will see a picture of dynamite if you have any in your inventory along with a number on the dynamite icon to show you how many bundles you have. This is also the same technique to setup mines correctly. Although with mines I find it much easier to hold
shift while placing mines for more precision.
Hope this helped.