app developing

Hello I need a responsive website. I would like it designed and built. I think it's what they call a responsive website". Where it is an app when browsed on a mobile phone and a website looking on a desktop. This particular app is going to deal in building or construction materials. Client will have to sign in with there mobile number as user name and generate there own password. A one time code will be sent to there registered phone number for authentication and then there account will be created. Clients will be able to mainly see or inquire different prices of different building materials or items. From this app my clients will be able to see both my goods and services and select appropriately what suits them. Some of the categories include [login to view URL]: (category) a) lake sand b) plaster sand. } (sub- category) c) yellow sand. d) white sand 2)Bricks a)clay brick c) soil bricks d) 99 bricks 3)Stones a) agreegate1/4 inch b) '' 1/2 inch c) '' 1. inch d) ,, 1¹/2 inch 4).Hard core a) block slates c) slates b) hard core 5). Cement a) Tororo cement b) Hima cement c) Kampala cement 5). Filling soil a) Normal soil b) Marram soil Now this is how it works. The list that I have tried to generate is my line of work. The items in numbers are the main categories of good I sale to my clients. But below them which I have called the sub categories, those are more specific items that a client would use to elaborate a little more on what they want But even from these subcategories we further have more options which I summarize as; [login to view URL], 2. type, 3. quantity, 4. price, 5. destination, 6. transport price 7. final price Eg. If you go to a supermarket and ask for sugar, they will ask you? 1. How much do you want? 2. What type do you want? 3. What color do you want? ...etc So in this case in our category No. We have SAND: Here we have so many type of sand so my idea is this. When a client clicks on the category SAND, he/she will be getting a dropdown menue of different types of sand. *Then he/she will select a type of sand of there interest. *Then the next step would be selecting the type of lorry (this tells us what quantity a client needs) which would be in form of a picture but also showing the price at the same time quantity *Then after selecting the type of sand, the size of the lorry, and it's price, then the client will go to a drop-down menu of where they want there product to go. From. Here we will have specific transport costs to be added to the item value to get the final value. As means of payment we have 2 system 1st one is cash on delivery 2nd is mobile money app something similar to this ( [login to view URL] ) which I will merging to this app as main means of payment. * from there, then we get to the point where the client has to in there own words can describe a little further more on there location Then there after the submission of there request I will be able to get an alert on my phone or mail where applicable. An arlert of transaction status and time duration on delivery will be shared to the client 's phone number. I have an example of the front page of this app/website on this link. And on top of that I want also to add something and that is houses for rent, under this a service provider will have to sign in as a service provider, then he will enter the description of the property , location , profile of the house eg two bed room or three bedroom , range of money contact and the details of property eg if he has the land title , and on the other side we have the customer who will open the application, choose the option for search a house, the location of the house, press search and a list of houses will show then he will select his best choice , the customer will not be able to see the contact of the service provider , it is only us the administrators who will be able to see their contacts . Thank you am looking forward to hearing from you .