You want to create a list with tab stops at the $2-$inch mark and $4-$inch mark. How do you accomplish this?

Click on the $2$ inch mark on the horizontal ruler. Then, click on the $4$ inch mark.

Click the Tabs button on the Insert Ribbon, type in the desired tab stop and then click Set.

Click Tabs button arrow on the Home Ribbon, and select $"2\mathrm{.}0"$ from the list. Then, click the Tabs button arrow on the Home Ribbon, and select $"4\mathrm{.}0"$ from the list.

$$ Click the Tab Alignment button until $2$ is visible and then click Set. Click the Tab Alignment button until $4$ is visible and then click set.