Thankyou Tommy

you wrote that you didn't understand the following apart...

!Apply some constraints
DK,3,UX,0,,,UY,UZ ! define a DOF constraint at a keypoint
DK,4,UY,0,,,UZ
! apply loads
FK,1,FY,-280e3 ! define a force load to a keypoint
FK,3,FY,-210e3
FK,5,FY,-280e3
FK,7,FY,-360e3

in this part not consider the following part, i think there is nop need of this part, this part just apply some constarints to structure whether support is fixed, roller or just a hinged.

!Apply some constraints
DK,3,UX,0,,,UY,UZ ! define a DOF constraint at a keypoint
DK,4,UY,0,,,UZ

but the following part

! apply loads
FK,1,FY,-280e3 ! define a force load to a keypoint
FK,3,FY,-210e3
FK,5,FY,-280e3
FK,7,FY,-360e3

this part is to define loads on the nodes, i just want to show an arrow at the nodes where user enters the force value. there is no need to
consider the value of the load.i think now it is more clear

and as you said about the input of the nodes....i will prompt about the node
nos, that wil be wriiten in the file...in the code u have written, it
draw line between the nodes enetered by user than it is fine with me.i think
there is problem in my text what i have given to u, i just wrote end node nos
of the element without knowing about that what is the actual node no. of some
node in the file. in my program what i did is that it assign the node no. in
following order...

first it gives higher preference to the coordinate of X.poiint having the higher
x-coordinate will assign as node 1, if two point have the same x-coordinate then
it will go to y-coordinate and give preference to point having higher Y-coordinate.
this is how my node nos are written in my text file.
i think now it will be clear to you that how file assign the node nos.
now you can see clearly that what are the end node nos of the elements and can make adjustment according to that
sorry for not making it more clear initially

thanks again

nsdhakar