This sentence keep showing up as a error in it. Could you please find the mistake and fix it for me.

To obtain a position as an Administrative Assistant which I can use my knowledge and experiences toward the growth of this company.

Add the word "in" before "which".

I'd also delete "toward" and use "in" there, too ... although that's not quite right either.

The mistake in the sentence is the incorrect use of the word "which." In this context, it should be replaced with "where" to indicate the specific company in which the administrative assistant wants to contribute their knowledge and experiences.

Corrected sentence:
To obtain a position as an Administrative Assistant where I can use my knowledge and experiences toward the growth of this company.