Inventor geometry constrain issue/Odd shape.......(Inventor 2012)

First of all i am newbie in inventor, i am leaning via youtube and online exercise so please take it easy, this online exercise told me to start with OPEN new (Standard.ipt) but when i open my new sheet of inventor i have (Standard (DIN).ipt which was what i used for this exercise and the other one is (Standard (mm).ipt.

so when i started just rough sketch by ignoring the actual given dims, this is what i was told when using draw stuff on inventor i should draw it out first and apply the constrain later. when i finished the sketch in large scale as shown on the first pic (called"my first sketch") and then when i applied on 4 the constrain to match with the given dims the geometry shape look very strange as the very bottom pic. Do your guys have special rule of constrain? why don't we draw in the actual given dims at the first place in Inventor just like in Autocad? when i was told to use STANDARD.ipt, is it in metric or English unit? i don't have anything on my Inventor that said Standard.ipt?

.... i was told when using draw stuff on inventor i should draw it out first

You were told wrong.

Sketch ONE line, rectangle or circle and dimension it immediately to give a sense of scale for the rest of the sketch (this was fixed in later releases of Inventor). Read this http://home.pct.edu/~jmather/SkillsUSA%20University.pdf

when i was told to use STANDARD.ipt, is it in metric or English unit? i don't have anything on my Inventor that said Standard.ipt?

You do have a Standard.ipt - you just don't know how to find it in your Templates folder. The units (in or mm) for the Standard.ipt is set when installing the software.

For now - just pick the Standard (mm).ipt or Standard (in).ipt template appropriate for the units you use.

Thank you, i found the Standard.ipt now, it was in different tab. And the geometry looks much better now by using your suggestion "Sketch ONE line, rectangle or circle and dimension it immediately to give a sense of scale for the rest of the sketch ",

Is there anyway that i can adjust the cross hair to make it bigger? can't find on the link.

Forget AutoCAD.