I would like to have some 2-3 days jungles trekking.

I chose Doi Inthanon National Park for this (near Chiang Mai).

Please tell me How can I get this trip?

Should I go to Doi Inthanon Park and get a trip there?

Or maybe I can get a tour from Chiang Mai?

Can I have trekking by myself?

I know I must pay some entering fee at the entrance to the park.

Of course It would be better to have some jungles trekking with a guide.

Jungle is jungle

And How much will such 2-3 days trip cost?

I would like to have some 2-3 days jungles trekking.

I chose Doi Inthanon National Park for this (near Chiang Mai).

Please tell me How can I get this trip?

Should I go to Doi Inthanon Park and get a trip there?

Or maybe I can get a tour from Chiang Mai?

Can I have trekking by myself?

Just about any trekking agency in Chiang Mai can arrange a guided trek around the Doi Inthanon region. And no, I don't think people should try trekking on their own. I have seen enough trekking guides get temporarily lost.