New Job

I'm so happy because soon I will have had a year in my new job. I love what I do in this job. I have learned many new things, and thanks to this job I have travelled a lot to other countries; well, in South America at least. :)
This is a multinational company. For that reason, I need to improve my English because I talk to people from other countries. (With is fine, but 'to' sounds a little better)
Sometimes I get very stressed at work and I have to work a lot of hours, but I like it, I think...

incorrect, corrections explanations :)

New Job

I'm so happy because soon I will have worked for a year in my new job. I love what I do in this job, I have learned many new things, and thanks forto this job I have the perfect aspect sounds more natural here because we are talking about events at unspecified times in the last year. travelled a lot to another countries, well in South America at least. :)
This is a multinational company, for that reason I need to improve my English because I talk with people from another countries.
Sometimes I get very stressfuled to be stressful is to cause stress, to be stressed is to feel stress at work and I have to work for many hours, but I liked it I think...

Nice notebook entry Mariana! Be careful with 'another' vs 'other': another is used as a singular thing in addition to something else, other can be any number of new things.