Final answer:
To merge and center cells A2:D2, select the range and use the Merge & Center option under the Home tab to combine and center the content.
Step-by-step explanation:
To merge and center the contents of a cell range, such as A2:D2, in a program, you need to first select the entire range by clicking and dragging from the first cell in the range (A2) to the last cell (D2).
Once the range is selected, you can find the Merge & Center option under the 'Home' tab in the 'Alignment' group. Clicking this button will combine the selected cells into one large cell and center the content within it. This feature is commonly used to create titles or headers that span across multiple columns.