To merge a group of cells:
(i) Select the cells to merge.
(ii) Right click and choose Cell ➝ Merge or choose Table ➝ Merge Cells from the menu bar.

Openoffice writer has the ability to insert and edit images in a more simply way.
(i) Place the insertion pointer where you want the image to appear
(ii) Select Insert \(\rightarrow\) Picture \(\rightarrow\) From file 
(iii) The insert picture dialog box appears where the picture gallery opens from which the desired picture can be selected.
(iv) If the picture is not in the gallery, then browse the pictures from the folder, choose the desired picture.
(v) Click on the Open button
(vi) The selected picture is inserted into the document.

OpenOffice Writer has a Find and Replace feature that helps to locate for a text inside a document and replace it with another word.
Click Edit Find & Replace (or) Ctrl + F
The Find & Replace dialog box appears as shown.
Steps to Find & Replace a text :
(i) Type the text you want to find in the Search forbox For Example : To search a word "Bombay" in a document and replace with "Mumbai", enter the word "Bombay" in the Search for box.
(ii) Enter the word " Mumbai" in the Replace with box and Click Find button, to start the search, the found word is highlighted and the first occurrence of "Bombay" is highlighted.
(iii) To replace text, click Replace button.
The highlighted word is replaced with the word given in the Replace with box.
(iv) Click Find All Writer selects all instances of the search text in the document.
All occurrences of Bombay are highlighted.
(v) Click Replace All button, Writer replaces all matches.
This will replace all occurrences of "Bombay" with "Mumbai".
(vi) Enable Match caseto perform the search case sensitively so that uppercase and lower cases are distinguished separately.
(vii) Enable Whole Words only to make the search more specific to words. For example, if you search for the word "Image", the command will only find Image" not "Imaging" "Images" etc.

The header is a section of the document that appears in the top margin, which displays the title or chapter name, author name of a document.
(i) Select from the main menu Insert \(\rightarrow\)Header \(\rightarrow\) Default.
(ii) The header text area is separated from the normal text area.
(iii) In the header area, Enter the text that is to be repeated in all pages or Select Insert \(\rightarrow\) Fields \(\rightarrow\) Title.
The footer is a section of the document that appears in the bottom margin of the page which displays the page number, date, time etc. which gets displayed on all the pages automatically.
(i) Select from the main menu Insert \(\rightarrow\) Footer \(\rightarrow\) Default
(ii) Place the insertion pointer in the footer part of the page.
(iii) Select Insert \(\rightarrow\) Fields \(\rightarrow\) Date to insert date in all the pages.
Inserting and Formatting page numbers 
The page numbers can be inserted by performing the following steps:
(i) Place the insertion pointer where you want to insert the page number
(ii) choose Insert \(\rightarrow\)Fields \(\rightarrow\)Page Number
(iii) The page number appears with gray background.
Normally, the page numbers appear as 1,2,3....., To change the numbering style, the following sequence of steps can be performed:
(i) Position the insertion pointer where the page number has to appear.
(ii) Select Format\(\rightarrow\) page, which will display the Page Style dialog box.
(iv) In the Layout settings, select the format drop down combobox
(v) Select the desired style and click OK button.

(i) Rightclick \(\rightarrow\)line spacing, select the type single, 1.5 or double.
(ii) Select the entire document by Edit\(\rightarrow\) Select All
(iii) Format- paragraph
(iv) The paragraph dialog box appears, click Indents & Spacing tab
(v) In the line spacing option, select the type and click OK button.

To insert rows or columns inside a table:
(i) Place the insertion pointer in the row or in the column where you would like to add new rows or columns and right-click.
(ii) Choose Row \(\rightarrow\) Insert - to insert a new row or Column \(\rightarrow\) Insert - to insert a new column. A dialog box will appear, from which you can select the number of rows or columns to insert. You can also set the position of the new rows or columns to Before or After.