4 channel Remote Control
4 channel means having the ability to send 4 individual values (maybe speeds?) at once.

Since the nRF24L01+ is a packet based system it is as simple as sending the different "channels" as different bytes (or groups of bytes if more than 0-255 or -128 to +127 is needed).

For instance, if you want 4 channels that can represent 0-255 then you need 4 bytes, and so you can set both sender and receiver to have a packet size of 4 bytes (for efficiency) and send a packet made up of the 4 channel values.

If you want to represent numbers bigger than that then you need to split the variable into bytes (two bytes for an int, 4 for a long) or create a struct to represent your packet of data. Of course you then need the sender and receiver to be set to a packet size at least big enough to contain the data, and both ends must agree on the packet size.