You have to basically use one of the rows and label it as zero. Then your going to need to enter a formula that is going to help you select each 7th row. You will want to use =MOD(ROW(),7). Also, I recommend using auto filter to filter out the other rows.
by using formula you can select every 7th row of a excel sheet, insert a column in the first row then add one formula MOD(ROW()) Copy down Copy/paste special/values Data/Filter.
Click on the Cells that you do not want to use. Then Click on Format-> Cell. Move to Protection Tab. Before this you have to protect this sheet. Learn more from the tips written there.
In order to do this, you would need to write a VB script to execute within Excel. You can also paste =MOD(ROW(),7) into the first cell in each row, then doa search for the number 7 and hide the rest.
okay this is not too hard, take and put your courser into first row, then seventh, fourteeth, and so forth. did this help you? Doing the courser is taking mouse and put it on, or in the box; which is the row.