成语 or expression that one is speaking about a topic he knows nothing about
Being modest is a good thing, but when you give a presentation, you should assure your audience that the content of your speech might not be ground-breaking, but is at least well thought out
Here is my suggestion:

大家好 - Hello everyone
以下是我努力硏修後得出來的成果 -  The following are the results of my hard work.
stating you have done your best and it is a well thought out speech

if you are not going to take any question:

如有不足之處，請各位多多包函 - If there are any deficiencies, please bear with me.

if you are going to take questions:

如有錯漏之處，請各位多多指教 - If there are any mistakes or omissions, please freely give me your advice.