Bansko, the popular ski resort is an important entry gate for the Pirin range. From the Bus station there are irregular minibus connections up the mountains, to Thebanderitsa and Vihren hut (base camp to hike in the area). Usually those Minivans leave after the arrival of Buses from Sofia. As an alternative you can take a taxi up, which will cost you about 15 US-Dollars.
Once inside, you will have to hike, the different huts and summits are connected by hiking trails.
There is a broad network of flagged trails through the mountains. The pirin tourist map 1:50'000(avalable at local shops) offers a good overview over trails and guest houses.
Most of the mountain huts offer cheap meals.
There is a network of mountain huts, which offer rooms and bungalows (bungalow for about 10 Dollars for two persons). Bring your sleeping bag. Alternatively there are marked camping areas around the huts.