You randomly select one card from a 52-card deck. find the probability of selecting a jack of club or the two of diamonds

Well, there are 52 cards. The probability of picking 2 out of 52 cards would be:

2/52!   Or in simplest terms, 1/26.

Good. Learning basic probability. The OR rule.
firstly, there are 4 jacks in a pack of 52.
but only 1 jack of clubs, so 
p(jack of clubs) = 1/52
secondly, there are 13 diamonds, and only one two of diamonds. so, 
p(two of diamonds) = 1/13.
The OR rule (sum)
P(jack of clubs OR two of diamonds)= (  1/52 + 1/13) = 0.096