Once you have your column labeled, you can start entering data into the column. Pressing ↵ Enter will take you to the cell below the current one. If you click the little arrow in the upper-left corner of the Worksheet, you can change the direction of data entry so that pressing ↵ Enter will take you to the next column on the same row.
If data is saved in an Excel spreadsheet, copy and paste it to Minitab. Highlight the data set saved in Excel. Right click the mouse and select copy. Go to Minitab and click the first cell below C1. Right click the mouse and select paste cells. Each column should represent one type of data. For example, if you are entering information about baseball teams, one column might be RBI, one might be Errors, and one might be Home Runs.