Thank you sooooo much ,It was very helpfull.

Grammatically, it is correct. Usually though, you get stressed out when you do physical or mental activity. Taking care of the kids; working long hours; doing hours of homework; etc. When you step in front of an audience you get nervous. If the nerves get worse then you start to break down. You don't really stress out in this situation.

Normally 'stressed out' means to suffer from high levels of physical or psycholgical stress. So you can use it but it's not usually used when referring to feelings that occur on individual occasions. Normally it describes someone who is very tense and anxious because of difficulties in their lives or from working too much. It is also informal language so we only use it in every day spoken English. It would be better to say I get stressed or I get very anxious/tense when I try to speak in front of an audience.