Short answer:
- arë "soil" vs arrë "nut"
- çaj "cut" vs qaj "cry"
- xham "glass" vs gjak "blood" (near-minimal).
More details:
In the International Phonetic Alphabet, here's how these contrasts would be written:
/ɾ/ vs /r/
/d͡ʒ/ vs /ɟ/
/t͡ʃ/ vs /c/
The first of these is the easiest to explain: r is a tap, while rr is a trill. In other words, in r your tongue flaps once, like a very short "d", and in rr it flaps several times. Spanish makes this same distinction, written the same way, and recordings should be easy to find: the classic minimal pair is pero "but" / perro "dog".
The second and third contrasts are more difficult. In Gheg Albanian the distinction is entirely lost, and this is spreading to some speakers of Tosk Albanian.
The sounds written ç and xh are "affricates", like in the English words church and jar. They're pronounced by stopping the flow of air, then releasing the obstruction partially. The sounds written q and gj on the other hand are "plosives", closer to the sounds in English keen and gear, pronounced by blocking the flow of air and then releasing it all at once.
English doesn't have Albanian's q and gj as distinct sounds, but they're very close to the pronunciation of English k and g before the vowel in "feed". These sounds also exist in Hungarian, where they're written ty and gy (as in "Magyar").