Creating tables for =vlookup and =if

I have to format a Microsoft Excel table using some assumptions and conditions.

The following are

• The number of paid vacation days that an employee is entitled to depends on their seniority and position as follows:
Contract employees are not entitled to any paid vacation; they only get paid for days they work.
Support Staff and Sales Staff are currently entitled to paid vacation days based on years of seniority as follows:
<1 year: 0 days
1 – 4 years: 10 days
5 – 9 years: 12 days
10 – 14 years: 15 days
>14 years: 20 days

Note: The only valid positions are Contract, Support Staff, and Sales Staff. If the position entered is not a valid position or is misspelled, the word Invalid should be displayed in the cell.

It is like I have to set up two different tables and use the =if function, i know then use the =vlookup table but I am not sure how to set the table up. any help would be appreciated, thank you.