since u r a Civil engineer I hope u have a salary more than 7000.

if so u can bring ur dad on a 6 month visit Visa.

U need following docs,

* Salary confirmation letter of ur's from company
* NOC from ur company for bringing ur dad here
* Copy of ur recidents permit and passport(Passport copy, ID Copy and Visa page of ur passport)
*Compoany ID copy (Munsha'a)
*Ur birth certificate attested from ur country foriegn embassy and qatar foriegn affairs(Not sure abt exact name of this ministry)
* Dad's birtn certificate too with above attestation
* Passport copy of dad's

U can apply through ur PRO or even by urself

please let me know if u need any further details

All the best