A margin is the space between the text and the edge of your document.
To format the margin of the paper as 1" in all sides, one need to follow the given steps:
1. Go to Format $\rightarrow$ Page in the menu bar.
2. Choose Page Tab.
3.Choose Page margin from the dialog box where Left, Right, Top and Bottom margin is to be set as 1".
4. Click OK.
Page margin is available in the Page tab of the Format tab of Menu bar.

(i) Header and Footer are some titles (such as Document Title, Author Name) or references (such as page no, number of pages, date) or remarks to be printed in the top (called as Header) and bottom of the page (called as Footer).
(ii) Headers and Footers are useful for including material that you want to appear on every page of the document.

(i) Sorting is the process of re-arranging data in ascending or descending order.
(ii) Sorting is the arrangement of data in certain order as per the requirement.

If a sheet is printed on multiple pages, you can set up certain rows or columns to repeat on each printed page.
Steps to print the title row on every page of the spread-sheet:
(i) On the Page Layout tab, in the Page Setup group, click Page Setup.
(ii) Under Print Titles, click in Rows to repeat at top or Columns to repeat at left and select the column or row that contains the titles you want to repeat.
(iii) Click OK.
(iv) Choose Format → Print Ranges → Edit.
(v) On the Edit Print Ranges dialog box, type the rows in the text entry box under Rows to repeat.

Given database is to be sorted on the basis of customer name in ascending order.
Step 1: Place the cell pointer in the field (customer name) to be sorted.
Step 2: Click Sort Ascending icon.
Database can be sorted in either way ascending or descending order depending upon the requirement

 

Header is the top margin of the page and Footer is the bottom margin of the page.
Application of Header and Footer:
(i) Header and Footer are some titles (such as Document Title, Author Name) or references (such as page no, number of pages, date) or remarks to be printed in the top (called as Header) and bottom of the page (called as Footer).
(ii) If we wish to get some information on every page, either on top or bottom of the page, we need to use header or footer as per the requirement.

Data base here will be a table with column name as register number, student name, Mark1, Mark2, and Mark3.
Below is the database as per the requirement given in the question:

For total, Formula used is =Sum (C2:E2) and then drag the cursor for below rows.
For average, Formula used is =F2/3 and then drag the cursor for below rows.