I bought a pella full glass storm door knowing that it would be too short for my opening(older house)... they wanted double the price for a custom door... I thought I could retrofit it with the adjustable sweep and a little creative carpentry ,but we`re talking 3 or 4 inches... and I`m not a professional carpenter...

I thought I wouldn`t be too bad building down from the top(lol) but,I`m not sure how it`s going to look...

Any suggestions?.

I'm not a carpenter either, (more a DIY enthusiast), and I don't have the answer to your question, but I wanted to share that I have had some success getting help with some of my home improvement issues from sites like Family Handyman (DIY Home Improvement Projects ? Do It Yourself Home Repair Guides - Family Handyman) and Ana White (Ana White | Free and Easy DIY Furniture Plans to Save You Money - it has a forum that is populated by way more advanced DIYourself-ers than myself). Plus, Lowe's has really informative videos on YouTube covering a wide range of topics. Hope that kind of helps :)

You might want to consider fabricating (or have a siding guy fabricate) a filler strip just like the bottom sweep and using that to fill the top few inches. May be able to find such a thing already fabricated at Home Depot or Lowe's. A lot depends on color.