Condoms can be purchased in drug stores, from coin-operated vending machines (in restrooms, bars and at the gas station), in health centers and by mail order. Sometimes people are afraid of what the sales person will think. But you should realize that you buy it only once in a while, which makes you nervous, but the shop assistant sells this item all the time and will probably think nothing of it.
In Europe you can buy any brand you want as long as it has the quality mark CE on the package. Then you know it meets the European standard.
Don’t use the condom if it has passed the ‘best before’ date (although it’s better to use an old condom than none at all), if the package is broken, if the condom is brittle or dried out, if the colour is uneven or changed or if it is unusually sticky.
Practise putting a condom on before having sex for the first time. Girls can practise on a penis-shaped object. When time comes you know how to put it on.
If a condom feels uncomfortable try a different type.