Corrections in red.  Stylistics and variants in blue.

My First Day on italki.com

To tell the truth, I've almost despaired of speaking English confidently. I've already been learning English (for) two and a half years; however, I'm afraid to speak English, and I thinking that I'm one of those people who have no talent for language learning. However, I also think I haven't done my best, so/and I'll try again with new resources and new hope.

The first day in italki.com

To tell the truth I've almost despaired to speak English confidently. I've been already learning English 2.5 years however I'm afraid to speak English and thinking that I am one of those people who have no talent for language learning. However I also think I didn't do my best and I'll try again with new resources and new hopes.

The first day in italki.com

To tell the truth I've almost despaired I'm desperate to speak English confidently. 

(You could also say: "I'm in despair over learning English fluently" or better: "I've lost hope in learning to speak English fluently". It's not wrong to use "despair" but it's a strong word choice. It's more common to use it as a noun or when talking about someone else.)

I've been already been learning English for 2.5 years however I'm afraid to speak English and I thinking that I am one of these those people who have has no talent for language learning. However I also think I didn't do my best and I'll try again with new resources and new hope. 

Don't despair! :)

I have the same frustrations in trying to learn spanish. However, I do not believe "those people" exist, and I think with perseverence we will get there! Much luck to you!

The first day in italki.com [My first day on italki]

To tell [you] the truth I've almost despaired [in my effort] to speak English confidently. I've been already been learning English for 2.5 [two and a half] years, however I'm afraid to speak English and I'm thinking that I may be one of those people who have no talent for language learning. However I also think that up to now I didn't do my best and therefore I'll try again with new resources and new hope.

Tatiana, I'm sure this is very common, I keep trying to remember vocabulary from other languages.

Have you had anybody actually tell you about your spoken English?

Stay positive, try speaking and see what happens!

Den