We installed a new ceiling fan/light and the instructions said we had to use a minimum 15 amp circuit (which we have) and when we try to turn it on at the switch, it doesn't come on bt it blows the circuit breaker (and all other electricity). What could be the problem?

Good morning and welcome to this forum.

From your description it appears that the wiring is incorrect.

Is this a brand new install or was there a light fixture where the fan is now installed?

If this is a brand new install, where did you get the source power for the fan? Did you run an entire new circuit or did you extend an existing circuit?

Can you attach pictures of the wiring to this thread?

Most likely your wiring is incorrect. In layman terms. Ceiling fans with a light have 4 wires to connect. White goes to the white (or common in your ceiling box) Black goes to black. If you connect only these 2 no fuse should blow so try this first. The remaining wires from the fan, usually red or blue and a white, are for the light. These connect to the same place as the white and black for the fan. White to white and red,or blue to the black. The fan and light should then operate from the switches on the fan.

This is a ceiling fan/light that my sister gave me. From the ceiling come 3 red wires twisted together, 3 white wires twisted together and a green wire. From there, we hooked the wires, white to white and black to red (there was no other red wire to the ceiling fan). There wound up to be 3 green wires (one for the light/fan, one from ceiling, and one was the ground). There are no pull chains to test the light or the fan separately. The switch is a special switch that you control the fan, light and power. Should I still attach pics?

This is an easy problem but without being able to test the circuit it requires some assumptions. #1 Now, since you describe the 3 red and 3 white in the ceiling box it is likely that the voltage between the red and white is 110 V. #2 The green wire should only be used for grounding. Check to see if it is connected to a screw in the ceiling box to confirm it is a ground It is also possible that the green wire was used as a switched leg from a light switch if there is one. See if you can tell if the green wire goes into a conduit in which case it my be used incorrectly. #3 Since the fan and light are switched from a wireless module we need to determine how the module is supposed to be wired. Any idea of the manufacturer and I will look it up?
So you know I have been a manufacturing engineer for 30 years.