You can either set the seeds yourself or you can buy young plants to pot up, its really up to you, but I will say it is getting a little late in the year for setting seeds yourself. But for future reference when setting cucumber seeds set the seed in a good compost in a 3 inch pot around 1.5cm deep the seed should be planted on its side not flat and then place them in a propergator with a constant temp of about 68F until they germinate. They can be tricky to look after from this stage as they don't like direct sunshine, so do need shading, too much water and they don't like draughts but do need ventilation! As with all gardening its a learning curve. Anyway if you buy your plants this year check to see if they are outdoor or indoor plants first, then choose which suits you. Pot them up in good compost into a large pot 8 inches or more, I tend to put a plastic collar around the stem of the plant as they don't always like water on this part and can rot off easily. I use an old pop bottle cut up and placed around the stem to create a collar, leaving around 2inch from the stem and push it into the compost and then you can water around the outside and none goes near the stem of the plant. It sounds a little complicated but it works. Hope this is of some help, everything is trial and error with gardening, so give it a go. As for when to pick them, when the fruit is big enough and depending on what variety it is, standard varieties or mini cucumbers. You could be picking as early as June but it depends when the plants were first set. One word of advice get all female plants as they are easier and you never get any bitter fruit. Good luck.