Colombia must to find a bigger economic cover.

So this part here, it looks like you made a typo on the word “Bigger” so it’s Bigger instead of Biger. You do not put the word “to” before the verb find in this context.

Colombia must to find a bigger economic cover, we can't ever depends ofn USA.

When you make a plural, that is, “we” you have to take away the s at the end of the sentence. Also, it looks like you switched “on” for “of.”

Like, they boughts us flowers and coffe,e, which we can sell to other nations.

so you would put a comma after “Like” and again, if you are talking about a plural subject, you take away the s from the verb. It also looks like you have a slight misspelling on “coffee,” and in order to connect that to “we can sell to other nations” you would probably use the word “Which”

We need to export more to be stronger economicly (i'm not sure about it exists).

so in order to keep your sentence flowing more, you want to put the word “in order to,” and there’s a misspelling on the word economically

To Critize our president for open the silk route with China is an aberration and a political ignorance.

I think what you are saying is “to criticize,” but i could be wrong. And it looks like you meant to say political.

To improve our nation, is also isto exchange our mentality.

The big countries negotiates with the world, not with an only country.