You may start with playing open strings using below pattern:
String numbers:
a. 6 3 2 1 2 3 (Practise thoroughly first, then move to second exercise)
b. 6 2 3 1 2 3
c. 6 1 2 3 2 1
Fingers:
1. Thumb should be used for 6th string.
2. 1st finger (Index) for 3rd string.
3. 2nd finger for 2nd string.
4. 3rd finger for 1st string.
Keep Playing!!