RE: cells
If you highlight across the cells you wish to merge you can use the Format menu, go to the alignment tab and tick the box towards the bottom of the dialog box which says merge. Once merged you can use the other options on that box to centre the text horizontally across the cells.
There is also a button on your formatting toolbar which merges and centres. It looks like a lower case 'a' with two arrows pointing away from the a. Like this
<--a--> if you find it that does the same job!
regards
Tracy