How do I increase numbers +1 by draging?

In Numbers, seed the series by entering 1 in the first position and 2 in the second position. Select both cells and drag the Fill Handle to extend the range. The Fill Handle is a little circle in the lower right corner of the selction.

Jerry

Adding to what Jerry said:

Numeric values will increment in steps set by the two seed values.

Single letters, text strings ending with a (single) numeral, times and dates will increment from a single seed, as shown below. Green filled cells are the seed values.

With two seed values, items in the first six columns in the example can also be made to increase (or decrease) in other than single unit steps. Add a third seed value (that breaks the pattern), and you'll get results like those in the last two columns.

This, and other topics about Numbers are covered in the Numbers '09 User Guide. This guide and the iWork Formulas and Functions User Guide are available for download through the Help menu in Numbers.

Regards,

Barry