Open a new browser tab or window and visit the Google Docs home page. Under the Sign In box, type in your Gmail email address and password. This is your one Google ID for all of Google's services, including Google Docs. Click the “Sign in” button to proceed. Upon logging in, you will be brought to the main directory. If you already have existing documents, you can see and access them from here. Click the large red circle with a plus sign on the lower right corner. A new window or tab will open with a blank document of the web-based word processor. A good signup sheet is tabular so that it will be easy to read and fill up. You will at least need to know how many columns or headers you will need for your signup sheet. Click the “Table” option from the main menu bar then “Insert Table.” Click on the dimensions you need for the table based on the number of columns and rows you will need. The table will be added to your document. On top of the table, type in the name of the signup sheet. Is it an attendance record, a volunteer signup sheet, a sign-in/sign-out sheet, or others? You can also add a description if you want. On the first row of the table, put the column titles. Since this is a signup sheet, you will need at least a column for names. The other columns will depend on what else you need to be filled up. It will make the signup sheet easier to count if you put row numbers in front of each row. Do so. Start with 1, until you reach the end. You can have more rows since you may not necessarily know how many will sign-up. When you're done, you can just simply close the window or tab. Everything is saved. You can access your signup sheet file from Google Docs or Google Drive.

Summary:
Go to Google Docs. Sign in. Create a new document. Insert a table. Name the signup sheet. Put the column headers. Put row numbers. Exit the document.