When you enter data into a cell in Excel, that cell becomes the active cell. The active cell is the one that has the blinking cursor in it. You can move to a different cell by using the arrow keys on your keyboard, or by clicking in a different cell with your mouse. When you move to a different cell, that cell becomes the active cell.
You can also move to a different cell by entering its address in the Name box, which is to the left of the Formula bar. For example, if you want to move to cell C5, you would enter C5 in the Name box and then press Enter on your keyboard. The active cell will then be C5.
If you want to move to a specific cell, you can also use the Go To command. To do this, click on the Home tab, and then in the Editing group, click on Find & Select. A drop-down menu will appear and from there you can click on Go To. In the Go To dialog box that appears, you can enter the address of the cell that you want to go to.
Once you've moved to the desired cell, you can start entering data. You can type in numbers, text, or formulas. To enter a formula, start by typing an equal sign (=). For example, if you wanted to sum cells A1 and B1, you would type =A1+B1 into the active cell. Once you've entered your data, press Enter on your keyboard and Excel will automatically move down one row for you so that you can enter data into the next cell.