Sorry I don't know any particular speakers to recommend, but here's some general info that might help.

Ohms are the units we use to measure electrical resistance, and it's a basic specification of speakers. In my limited experience (in the U.S.), 8 ohms has been by far the most common rating. I have seen 4 ohm speakers, and I had an old (1960 vintage) amp that had terminals for 4, 8, and 16 ohms, but 99% of the speakers I've seen are 8 ohms. Assuming no error in the specs Jon found for you, you want 8 ohm speakers (others will work but not as well).

I've had impedance defined to me, but I never quite grasped it and don't remember the definition. It seems to me that a layman shouldn't have to know what impedance speakers he needs--the salesman should be able to advise.

The other spec Jon supplied is wattage, which is the unit of electrical power. "RMS" mean "root mean square," which essentially means average, as opposed to peak or maximum wattage. Since it's a per channel rating, each speaker needs to be able to handle 25 watts of consistent power. A good hi-fi salesman should be able to direct you to suitable choices.

Less honorable companies sometimes advertise peak wattage or total RMS wattage (in this example 2x25=50), either of which tend to mislead buyers into thinking they're getting a more powerful amp than they really are.

My understanding is that it's OK, perhaps desirable, to have speakers that can handle somewhat more power than the amp's rating. Getting speakers that are significantly mismatched to the amp can be a problem. If they can't handle it (say speakers rated at 15 watts) they will distort at any but the lowest volume levels. If they're rated for much higher wattage, the amp can't really drive them properly. Again, a good hi-fi salesman should be able to help here.

The old standard advice is to get speakers of a higher quality level than the rest of the system, for two reasons: to essentially eliminate any chance of distortion; and to be in a position to upgrade other system components without having to replace the speakers also. Quality level is not the same as wattage rating, though the two tend to go hand in hand to some degree.

To sum up: Get 8 ohm speakers. Make sure they can EASILY handle 25 watts RMS each. If your budget's not really bursting, don't scrimp.