Sorry, quite a busy day ( ouch my sore feet ).
Shreeit, here's how I did the blueprint.
As I said, export your image if done in another apps as a grayscale to PS.
Open Image.
Click image layer to make it the active layer, Control + click gray channel in channels palette. Then, CTRL+SHIFT+ I to inverse and select the image pixels. Create new layer. Fill selection with black. CTRL + D to deselect.
Delete contents of background layer. What you did is extract the image from the solid white background unto its own layer.
Convert image mode to RGB, Don't Flatten.
Set foreground color to #AE3AF7 (for drawing image) and background to #C179F4 (for paper texture).
Make background layer into an editable layer by pressing ALT + double clicking the background layer in palette.
With this layer active, Press CTRL + delete to fill with background color. Then, Filter>Noise>Add Noise at 8% set to Uniform, Monochromatic. Control + F to apply Noise a second time.
Filter>Blur>Gaussian Blur at 0.6 pixels.
Lower the layer opacity to if you find it too dark.
Next, the image. With the image layer as the active layer, Press SHIFT + ALT + Delete to fill opaque pixels in the layer with foreground color. Deselect. Repeat above steps for Noise and Blur.
If you find the image on the image layer too light or thin, copy it on a new layer and merge.
Flatten the layers.
Basically, your done. Now, there is discoloration in my image -imperfections in the blueprinting process. Just like the output of my service bureau (yeeks, [shhh] hope they don't read this

. )
All you need is the Dodge and Burn Tool both set at 25% exposure as well as the Sponge tool set at desaturation with a 50% flow. Click and drag to recreate those vertical bandings. But not too much as to end up with something I'd usually reject from my service bureau

.
One last tip - an architectural or a schematic blueprint usually do not have solid colors with the exception of walls, certain columns and small details. It has what we call hatching, a pattern fill of dots or criss-crossing lines. Extra Large text that are details for say - a logo or wall emblem are rendered this way.
Unless you want it in a solid color, but the blueprint effect you're after won't look right.
Hope this helps you with your web page. If there are parts you dont understand, holler.
vee