Here is the easiest way, a simple use of the ampersand ( & ) sign.
In the formula bar1. Enter an equals(=) sign
2. Click the first text cell to join
3. Enter an ampersand( & ) sign
4. Click the second text cell to join
5. Do this as many time as you like
If you would like to add a space or additional text between cells, enclose it between quotation marks.